But it's not actually clear why is it critical that PID 1 is simple (and if situation is so much worse with systemd).
Xorg, which on desktop is as critical as init to keep running, is not really simple.
kernel, which is also as critical as init to keep running, and it is *much* *much* more complex than systemd. systemd is not at the "bottom layer" of the system, there's the whole of kernel underneath still.
And one common myth is that systemd has these so many features and systemd is pid 1 therefore pid 1 is this huge bloated monster that does udev, logging and NTP, right? Wrong; actually, just the core bits of systemd run in pid 1 and the rest is compartmentalized in a bunch of separate daemon processes.
So, this "increased complexity" issue is not really as bad as it sounds, realistically.